At work, I use my personal computer which runs on Ubuntu, and I connect it to the network by plugging in an RJ45 cable. When I do this, Firefox automatically redirects me to a captive portal where I enter my institutional credentials, and I’m able to access the internet.
One of my colleagues uses a Windows laptop provided by the institution, and they typically connect to the network using Wi-Fi. We tried connecting the laptop to the network using an ethernet cable so that we could access the printers, but it didn’t work. Even though my colleague has their own credentials that work on the Wi-Fi captive portal, they couldn’t access the internet using ethernet. We couldn’t even get to the captive portal page.
I have some information about the connection because it works on my Ubuntu PC, but the IT service is not very helpful, and they often reset computers without warning. So, we’re trying to figure out how to fix the problem on our own.
Edit (David’s comment): Here’s the ipconfig output from the Windows PC (in French, sorry):
Carte Ethernet Connexion au réseau local :
Suffixe DNS propre à la connexion. . . :
Adresse IPv6 de liaison locale. . . . .: fe80::844f:5907:7552:c1f%10
Adresse IPv4. . . . . . . . . . . . . .: 192.168.137.
Masque de sous-réseau. . . . . . . . . : 255.255.255.0
Passerelle par défaut. . . . . . . . . :
Ifconfig from ubuntu pc successfully connected :
enp0s31f6: flags=4163<UP,BROADCAST,RUNNING,MULTICAST> mtu 1500
inet 172.31.195.104 netmask 255.255.0.0 broadcast 172.31.255.255
inet6 fe80::a69e:fb0d:2790:a94f prefixlen 64 scopeid 0x20<link>
ether d8:9e:f3:7a:f4:17 txqueuelen 1000 (Ethernet)
RX packets 132465 bytes 82002810 (82.0 MB)
RX errors 0 dropped 0 overruns 0 frame 0
TX packets 57868 bytes 7999429 (7.9 MB)
TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0
device interrupt 20 memory 0xf7100000-f7120000
lo: flags=73<UP,LOOPBACK,RUNNING> mtu 65536
inet 127.0.0.1 netmask 255.0.0.0
inet6 ::1 prefixlen 128 scopeid 0x10<host>
loop txqueuelen 1000 (Boucle locale)
RX packets 14066 bytes 1383740 (1.3 MB)
RX errors 0 dropped 0 overruns 0 frame 0
TX packets 14066 bytes 1383740 (1.3 MB)
TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0
C:\Users\Mahdi>ipconfig /all
Configuration IP de Windows
Nom de l'hôte . . . . . . . . . . : Wi-HP
Suffixe DNS principal . . . . . . :
Type de noeud. . . . . . . . . . : Hybride
Routage IP activé . . . . . . . . : Non
Proxy WINS activé . . . . . . . . : Non
Carte réseau sans fil Connexion réseau sans fil :
Statut du média. . . . . . . . . . . . : Média déconnecté
Suffixe DNS propre à la connexion. . . :
Description. . . . . . . . . . . . . . : Intel(R) Centrino(R) Advanced-N 6205
Adresse physique . . . . . . . . . . . : A0-88-B4-BA-CA-C8
DHCP activé. . . . . . . . . . . . . . : Oui
Configuration automatique activée. . . : Oui
Carte Ethernet Connexion au réseau local :
Suffixe DNS propre à la connexion. . . :
Description. . . . . . . . . . . . . . : Intel(R) 82579LM Gigabit Network Con
nection
Adresse physique . . . . . . . . . . . : 10-1F-74-C1-20-A7
DHCP activé. . . . . . . . . . . . . . : Non
Configuration automatique activée. . . : Oui
Adresse IPv6 de liaison locale. . . . .: fe80::844f:5907:7552:c1f%10(préféré)
Adresse IPv4. . . . . . . . . . . . . .: 192.168.137.1(préféré)
Masque de sous-réseau. . . . . . . . . : 255.255.255.0
Passerelle par défaut. . . . . . . . . :
IAID DHCPv6 . . . . . . . . . . . : 237774807
DUID de client DHCPv6. . . . . . . . : 00-01-00-01-1F-A8-53-04-10-1F-74-C1-20
-A7
Serveurs DNS. . . . . . . . . . . . . : fec0:0:0:ffff::1%1
fec0:0:0:ffff::2%1
fec0:0:0:ffff::3%1
NetBIOS sur Tcpip. . . . . . . . . . . : Activé
Carte Tunnel isatap.{5250A0DA-1520-4575-BE9C-C382A896E459} :
Statut du média. . . . . . . . . . . . : Média déconnecté
Suffixe DNS propre à la connexion. . . :
Description. . . . . . . . . . . . . . : Carte Microsoft ISATAP #2
Adresse physique . . . . . . . . . . . : 00-00-00-00-00-00-00-E0
DHCP activé. . . . . . . . . . . . . . : Non
Configuration automatique activée. . . : Oui
Carte Tunnel isatap.{EB8A8081-3958-4F9A-9BC8-0942FFEC74F2} :
Statut du média. . . . . . . . . . . . : Média déconnecté
Suffixe DNS propre à la connexion. . . :
Description. . . . . . . . . . . . . . : Carte Microsoft ISATAP #3
Adresse physique . . . . . . . . . . . : 00-00-00-00-00-00-00-E0
DHCP activé. . . . . . . . . . . . . . : Non
Configuration automatique activée. . . : Oui
Carte Tunnel isatap.{EC57BAE2-C7AE-4947-BA24-73455A2F55BE} :
Statut du média. . . . . . . . . . . . : Média déconnecté
Suffixe DNS propre à la connexion. . . :
Description. . . . . . . . . . . . . . : Carte Microsoft ISATAP
Adresse physique . . . . . . . . . . . : 00-00-00-00-00-00-00-E0
DHCP activé. . . . . . . . . . . . . . : Non
Configuration automatique activée. . . : Oui
Carte Tunnel Teredo Tunneling Pseudo-Interface :
Statut du média. . . . . . . . . . . . : Média déconnecté
Suffixe DNS propre à la connexion. . . :
Description. . . . . . . . . . . . . . : Teredo Tunneling Pseudo-Interface
Adresse physique . . . . . . . . . . . : 00-00-00-00-00-00-00-E0
DHCP activé. . . . . . . . . . . . . . : Non
Configuration automatique activée. . . : Oui
C:\Users\Mahdi>netsh interface ipv4 show address:
Configuration pour l'interface « Connexion réseau sans fil »
DHCP activé: Oui
Adresse IP : 172.20.10.13
Préfixe de sous-réseau : 172.20.10.0/28 (masque 255.255.255.24
0)
Passerelle par défaut : 172.20.10.1
Métrique de passerelle : 0
Métrique de l'interface : 25
Configuration pour l'interface « Connexion au réseau local »
DHCP activé : Non
Adresse IP : 192.168.137.1
Préfixe de sous-réseau : 192.168.137.0/24 (masque 255.255.255.
0)
Métrique de l'interface : 20
Configuration pour l'interface « Loopback Pseudo-Interface 1 »
DHCP activé : Non
Adresse IP : 127.0.0.1
Préfixe de sous-réseau : 127.0.0.0/8 (masque 255.0.0.0)
Métrique de l'interface : 50
3 Answers
Introduction
Connecting to the internet is essential for most people, whether it’s for work or personal use. However, sometimes issues arise, and it’s not always clear how to solve them. In this blog post, we will discuss a problem where a business Ethernet connection displays a captive portal on Ubuntu rather than Windows. We will explore the possible reasons for this issue and provide some potential solutions.
The Problem
The problem is that a colleague who uses a Windows laptop provided by their institution cannot access the internet using Ethernet. When they connect to the network using Wi-Fi, they can access the internet without any issues. However, when they connect to the network using Ethernet, they cannot even get to the captive portal page. The captive portal is the page that requires users to enter their institutional credentials to access the internet.
In contrast, when the author connects their personal computer, which runs on Ubuntu, to the network using Ethernet, Firefox automatically redirects them to the captive portal page. They can enter their credentials and access the internet.
Possible Reasons
There are several possible reasons why the Windows laptop cannot access the internet using Ethernet while the Ubuntu computer can.
IP Address Configuration
One possible reason is that the IP address configuration is different between the two computers. The IP address is a unique identifier that allows the computer to communicate with other devices on the network. If the IP address is not configured correctly, the computer may not be able to connect to the internet.
In the ipconfig output provided by the author’s colleague, the IPv4 address is incomplete. It only shows the first three octets (192.168.137.), which is not a complete IP address. This could be an indication that the IP address is not configured correctly on the Windows laptop.
In contrast, the ifconfig output from the author’s Ubuntu computer shows a complete IPv4 address (172.31.195.104). This suggests that the IP address is configured correctly on the Ubuntu computer.
Network Adapter Driver
Another possible reason is that the network adapter driver on the Windows laptop is not installed or outdated. The network adapter driver is the software that allows the computer to communicate with the network adapter, which is the hardware that connects the computer to the network.
If the network adapter driver is not installed or outdated, the computer may not be able to connect to the internet. This could be why the Windows laptop cannot access the captive portal page when connected via Ethernet.
Firewall Settings
Firewall settings could also be a possible reason for the problem. A firewall is a security program that monitors and controls incoming and outgoing network traffic. If the firewall settings are too strict, it may prevent the computer from accessing the internet.
Potential Solutions
Now that we have explored the possible reasons for the problem let’s discuss some potential solutions.
Check IP Address Configuration
The first potential solution is to check the IP address configuration on the Windows laptop. The IP address should be set to obtain an IP address automatically. To check this, follow these steps:
1. Open the Network and Sharing Center by right-clicking on the network icon in the system tray and selecting “Open Network and Sharing Center.”
2. Click on “Change adapter settings.”
3. Right-click on the Ethernet adapter and select “Properties.”
4. Select “Internet Protocol Version 4 (TCP/IPv4)” and click on “Properties.”
5. Select “Obtain an IP address automatically” and “Obtain DNS server address automatically.”
6. Click on “OK” to save the changes.
Update Network Adapter Driver
The second potential solution is to update the network adapter driver on the Windows laptop. To do this, follow these steps:
1. Open the Device Manager by right-clicking on the Start menu and selecting “Device Manager.”
2. Expand the “Network adapters” category.
3. Right-click on the Ethernet adapter and select “Update driver.”
4. Select “Search automatically for updated driver software” and follow the on-screen prompts to complete the update.
Disable Firewall
The third potential solution is to temporarily disable the firewall on the Windows laptop. To do this, follow these steps:
1. Open the Control Panel by searching for it in the Start menu.
2. Click on “System and Security.”
3. Click on “Windows Defender Firewall.”
4. Click on “Turn Windows Defender Firewall on or off.”
5. Select “Turn off Windows Defender Firewall” for both private and public networks.
6. Click on “OK” to save the changes.
Conclusion
In conclusion, a business Ethernet connection displaying a captive portal on Ubuntu rather than Windows could be due to several reasons, including IP address configuration, network adapter driver, and firewall settings. We have discussed some potential solutions to these issues, including checking the IP address configuration, updating the network adapter driver, and disabling the firewall temporarily. By following these potential solutions, the problem should be resolved, and the Windows laptop should be able to access the internet using Ethernet.
It looks like the Windows laptop is not able to access the internet through the Ethernet connection. There are a few things you can try to troubleshoot this issue:
- Make sure that the Ethernet cable is properly connected to both the laptop and the network.
- Check the Ethernet adapter settings on the Windows laptop. Make sure that the adapter is enabled and that it is set to obtain an IP address automatically (DHCP).
- Check if there is a firewall or antivirus software that may be blocking the connection.
- Try using a different Ethernet cable or port on the network.
- If the laptop is able to connect to the internet through Wi-Fi, try disabling the Wi-Fi adapter and see if the Ethernet connection starts working.
- Check if there are any system or network settings that may be preventing the laptop from accessing the internet through the Ethernet connection.
- If the Ethernet connection still does not work, you may need to contact your IT department or network administrator for further assistance. They may be able to identify the cause of the issue and provide a solution.
If the above troubleshooting steps did not resolve the issue, you may want to try the following additional steps:
- Check if the Ethernet port on the laptop is functioning properly. You can do this by connecting a different device (such as a smartphone or another laptop) to the same Ethernet port and see if it is able to access the internet.
- Check if the Ethernet port on the network is functioning properly. You can do this by connecting a different device (such as a smartphone or another laptop) to a different Ethernet port on the network and see if it is able to access the internet.
- Check if there are any network settings or policies in place that may be preventing the Windows laptop from accessing the internet through the Ethernet connection. You may need to contact your IT department or network administrator for assistance with this.
- If all else fails, you may need to reset the network settings on the laptop or try using a different Ethernet adapter.
I hope this information helps. If you have any further questions or need additional assistance, please don’t hesitate to ask.
If a network functions properly on a Windows operating system but not on Linux on the same computer, there could be several reasons for this:
- The network configuration may be partially static and require manual setup in Linux, just like in Windows (such as IP address, subnet mask, gateway, and DNS).
- There may be a system-wide proxy configuration in Windows that is not automatically applied in Linux.
- The network may use 802.11X authentication, which can be checked in the Ethernet adapter properties of the Windows network configuration. 802.11X is a security configuration of the network port used to prevent unauthorized access to the network. Windows can authenticate itself to the network switch using certificates and a private key, and only if the system passes this authentication will access to the network be granted. Linux does not have access to these certificates, which means that it fails the authentication process and is redirected to the captive portal.
It is not possible to change this behavior on your own computer. Only a network administrator with access to the switch your computer is connected to can make these changes.